Mail is goining missing to one supplier.

Hi,

We are able to send mail all over the world. But we seem to have problems sending to China. We have a few suppliers there. Now from time to time when we send them mail they never receive it. We don't get any Non-delivery reports from them either. (again China only). I would like to treace an e-mail and see where it goes before it goes lost, or have some sort of way to figure out what happens to the mail.

Thanks!